1. Field of the Invention
The present invention relates generally to color correction of an image signal, and more particularly, to tuning color correction matrix coefficients with a visualization aid from transformation into an XY plane.
2. Background of the Invention
Equation 1 below shows a 3×3 color correction matrix used for color correction of an image signal comprised of color signals Rin, Gin, and Bin:
                              (                                                    Rout                                                                    Gout                                                                    Bout                                              )                =                              (                                                                                r                    ⁢                                                                                  ⁢                    1                                                                                        g                    ⁢                                                                                  ⁢                    1                                                                                        b                    ⁢                                                                                  ⁢                    1                                                                                                                    r                    ⁢                                                                                  ⁢                    2                                                                                        g                    ⁢                                                                                  ⁢                    2                                                                                        b                    ⁢                                                                                  ⁢                    2                                                                                                                    r                    ⁢                                                                                  ⁢                    3                                                                                        g                    ⁢                                                                                  ⁢                    3                                                                                        b                    ⁢                                                                                  ⁢                    3                                                                        )                    ⁢                      (                                                            Rin                                                                              Gin                                                                              Bin                                                      )                                              Equation        ⁢                                  ⁢        1            
As shown, RGB (red, green, and blue) values of color signals Rin, Gin, and Bin are tuned to Rout, Gout, and Bout with the 3×3 matrix. That is, the tuned image signal has RGB values of Rout, Gout and Bout as shown in Equations 2, 3, and 4 below:Rout=r1*Rin+g1*Gin+b1*Bin  Equation 2Gout=r2*Rin+g2*Gin+b2*Bin  Equation 3Bout=r3*Rin+g3*Gin+b3*Bin  Equation 4
According to such mathematical models, matrix coefficients for a desired color correction such as r1, g1, b1, r2, g2, b2, r3, g3, and b3, may be obtained. Herein, influence of gamma and shading are considered for the color correction coefficients for desired color correction. However, intuitive estimation of the color correction coefficients of the matrix for the target color correction is difficult using the mathematical models.
In the prior art, such color correction coefficients are not intuitively recognized. Instead in the prior art, the image signals are tuned by repeatedly modifying the color correction coefficients based on personal experience without any regulated rules. Therefore, tuning the image signal according to the prior art is time consuming and requires much effort.